This application is based on and claims priority to Japanese Patent Application Nos. Hei 11-269968, filed Sep. 24, 1999, and Hei 11-292280, filed Oct. 14, 1999, the entire contents of which are hereby expressly incorporated by reference.
1. Field of the Invention
This invention relates to a cowling for an outboard motor, and more particularly to an air intake construction of the cowling.
2. Description of Related Art
A typical outboard motor employs an internal combustion engine for powering a propulsion device such as a propeller. A protective cowling normally encloses the engine therein to present a neat appearance and to protect the engine. The cowling protects the engine from being wetted by the water in which the outboard motor is operated. Water, especially salt water, tends to damage engine components.
The protective cowling defines a generally closed cavity in which the engine is contained. The engine, however, must be supplied with copious amounts of air through an air induction device for combustion in its combustion chambers. For this purpose, the air induction system of the engine has an air inlet opening that is open to the cavity within the cowling. Conventionally, the protective cowling includes a rearwardly positioned, generally upwardly facing air intake duct that permits air flow into the cavity. The intake duct usually extends upwardly from the cavity into an additional small cavity, which defines an air compartment. Air flow through the duct often is normal to the direction of air flow into the air compartment to cause water to drop out of the air flow before the air moves through the duct. This arrangement thus inhibits water from entering the main cavity of the cowling; however, it does not entirely prevent water from entering the cavity through the duct.
The air inlet opening of the engine induction system is normally positioned at a front portion of the main cavity. Thus, the air must travel across the engine body from the air duct to the air inlet opening. This air flow advantageously cools various engine components, but it is also warmed through this process, which reduces charging efficiency. This problem is exacerbated with outboard motors employing four-stroke engines, as these engines tend to run hotter than two-stroke engines.
The present invention involves the recognition that a need exists for an improved cowling that can supply relatively cool air containing little or no water to the induction device. The present invention also acts to smooth the flow of air and to reduce noise generated as air is taken into the engine compartment. Still further, the present invention aids removal of water from air taken into tie cowling.
In accordance with one aspect, the present invention provides an outboard motor comprising an internal combustion engine and a cowling assembly enclosing the engine. The engine drives a propulsion device and includes an air induction device. The air induction device includes an air inlet that opens into a space defined within the cowling assembly. The cowling assembly includes an air compartment and has an air intake duct structure adapted to direct air from the air compartment into the space. The air duct structure includes a plurality of elongated passages formed therehrough.
In accordance with another aspect of the present invention, an outboard motor comprises an internal combustion engine and a cowling assembly enclosing the engine. The engine is adapted to drive a propulsion device and includes an air induction device, which includes an air inlet that opens into a space defined within the cowling assembly. The cowling assembly includes a front air compartment and a rear air compartment each of which have an air intake duct adapted to direct air from the air compartment into the space. A conduit communicates between the front and rear air compartments.
In accordance with yet another aspect, the present invention provides an outboard motor comprising an internal combustion engine and a cowling assembly enclosing the engine. The engine drives a propulsion device and includes an air induction device, the air induction device including an air inlet that opens into a space defined within the cowling assembly. The cowling assembly includes an air compartment having an air intake duct adapted to direct air from the air compartment into the space. A drain passage is formed through a wall of the air compartment. A conduit extends from the drain passage into a lower portion of the cowling assembly.
Further aspects, features and advantages of this invention will become apparent from the detailed description of the preferred embodiments which follow.